The present invention relates to a conduction assist member used for connection between conductors for various electronic equipments, manufacturing method of the same, a connector using the same and an integrated circuit socket using the same.
A conduction assist member functions to assist electrical conduction between connecting elements of a connector by being made to intervene between the connecting elements.
There are several types of connector electrically connecting conductors to each other. For example, in one type of connector, connecting elements have flat conductive surfaces. They are laid one on top of the other and brought into contact with each other so that electrical conduction is made. In another type of connector, one of connecting elements is a plug and the other is a socket, and the plug is fitted in the socket to bring an outer circumferential surface of the plug into contact with an inner circumferential of a socket hole so that the electrical conduction is made. In order to secure sufficient electrical connection in such a connector, it is necessary to bring the connecting elements into close contact with each other. However, if the connecting element has a distortion, or dust or the like exists between the connecting elements, the contact area between the connecting elements becomes small. As a result, close contact between the connecting elements is prevented and electrical connection becomes incomplete.
As a means for solving the above-mentioned problem, Japanese Utility Model Publication (Kokoku) No. 1-22230 discloses a conduction assist member in which a plurality of blades are disposed between two annular frames with a constant interval and obliquely oriented with respect to an outer circumferential surface of a plug, the conduction assist member being disposed around an inner circumferential surface of a socket hole or the outer circumferential surface of the plug. Japanese Utility Model Publication (Kokoku) No. 51-8710 discloses a conduction assist member in which tongue pieces both ends of which are connected to an annular metal band provided with a plurality of cuts, are disposed around an inner circumferential surface of a socket hole or an outer circumferential surface of a plug so that the tongue pieces are obliquely oriented with respect to the outer circumferential surface of the plug.
On the other hand, an integrated circuit such as an IC or an LSI is mounted on a substrate or the like through an integrated circuit socket. Thus, in order to secure sufficient electrical conduction, it is necessary that a contact substrate of the integrated circuit socket, that is, a portion assisting conduction between the integrated circuit and the substrate, is brought into close contact with both of a terminal of the integrated circuit and a terminal formed in the substrate. Further, the contact substrate of the integrated circuit socket used for mounting is required not only to be thin by the demand for miniaturing information processing equipments or the like in recent years but also to have high speed performance in accordance with increase of an amount of information to be processed.
As conventional contact substrates for integrated circuits, the following are exemplified. That is, one contact substrate uses a terminal contact member 35 in which a curved portion 27 is formed to give elasticity in an up-and-down direction, and a support portion 29 for a terminal is formed (FIG. 4(a)). Another contact substrate includes a silicone rubber 30 in which metal thin wires 31 are buried at a high density (FIG. 4(b)). A third contact substrate includes a rubber sheet 32 between both surfaces of which conductive grains 33 are disposed in lines, and when the contact substrate is compressed by a spherical terminal 24 of an integrated circuit, the conductive grains 33 at a compressed portion are brought into contact with one another (FIG. 4(c)). A fourth contact substrate includes a terminal contact member 35 which is buried in a sheet while an end of the terminal contact member is supported by a coil spring 34 and the other end thereof protrudes from the sheet (FIG. 4(d)). A fifth contact substrate includes a terminal contact member 35 which is formed of a randomly wound wire of a conductive material and is buried in a sheet while both ends thereof protrude from the sheet (FIG. 4(e)).
However, the above-mentioned conduction assist member is used in a socket-plug type connector and especially the conduction assist member as disclosed in Japanese Utility Model Publication (Kokoku) No. 51-8710 has a problem in durability such that the tongue pieces or blade portions are damaged or abraded due to repeated use. Furthermore, the conduction assist member has a problem that it must be prepared in compliance with different standards so that it matches with sizes of connectors.
As to the contact substrates for integrated circuits, the contact substrate shown in FIG. 4(a) is inferior in high speed performance and poses a problem that it cannot be used for an integrated circuit socket for mounting.
The contact substrate shown in FIG. 4(b) can hardly be applied to an integrated circuit of the LGA type although it is superior in high speed performance.
Also, with respect to the contact substrate shown in FIG. 4(c), there are problems that conduction is unstable due to a fact that the conductive grains 33 in a line are not brought into sufficient contact with each other or are brought into contact with the conductive grains 33 in another line.
Further, since the contact substrate shown in FIG. 4(d) is required to be thick inevitably due to the structure thereof, it exhibits problems in that it exhibits inferior high speed performance and that it is not suited for mounting use.
Furthermore, the contact substrate shown in FIG. 4(e) poses a problem that it has diversified conduction paths and its electric characteristics become unstable.